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27 Cards in this Set
- Front
- Back
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Tbx5 and Tbx4 are what? where are they? what do they stimulate?
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homeobox genes that stimulate the expression and secretion of fibroblast growth factor 10 (FGF-10) in mesodermal cells
5 in forelimbs 4 in hindlimbs |
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FGF10 stimulates what?what process does this stimulate? feedback loop?
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FGF-10 stimulates FGF-8.
FGF-8 stimulates epi to mesenchymal interaction (not transformation!) positive feedback loop |
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The AER is present in which limbs? what if you don't have it?
Which axis is it located along? which enzymes are where? |
both forelimb and hindlimbs! no AER=no limbs!
located along D-V axis. separates dorsum and palmar aspects of hand. r-Fng is dorsal En-1 is ventral both crucial for AER-needs both! made up of ectoderm (acute ectodermal ridge) that signals mesoderm and vice versa |
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if you remove the AER and later and later period of development, what happens?
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you more limb/less removed
basically, the earlier you remove AER, the more of the limb that doesn't develop |
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the lateral plate mesoderm gives rise to what?
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the skeleton, connective tissue, blood vessels
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somites give rise to what?
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muscle
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neural crest cells give rise to what?
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schwann cells, sensory nerves, pigment cells
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the neural tube gives rise to what?
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motor axons
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what is the ZPA and what does it provide?
what is it's signalling molecule produced by ZPA? what stimulates this production? |
zone of polarizing activity in posterior aspect of limb bud that provides asymmetry of the limb
sonic the hedgehog is produced by ZPA when the ZPA is stimulated by retinoic acid |
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what/where is the progress zone?
transcription factors in this area? |
region of actively dividing cells immediately beneath the AER
Msx-1 (proximal) Msx2 (distal) |
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the progress zone is important for establishing what structures along the Prox-Distal axis?
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skeletal structures!
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anterior vs. posterior axis...?
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anterior=thumb
posterior=pinky |
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FGF-8 expressed where? stimulates what?
FGF-4 expressed where? stimulates what? |
FGF-8 along entire AER-stimulates Msx-1=progress zone
FGF-4 expressed in posterior half (pinky)-Shh=ZPA |
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Hox d genes: how are they spread out/divided?
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hox d 9-13,
9 underlies everything, then 10 (more distal) then 11 (even more distal) etc...to 13 Hox a is very similar |
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mutation in hox d 13= what?
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mutation in the digits (hox 13 is most distal of hox d regions)
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name the axes and the hoeobox genes expressed in each
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Proximal Distal=Msx1, Msx2, HoxA, HoxD
Anterior-Posterior:Hox D differential expression Dorsal-Ventral: Lmx1 (dorsal-stimulated by Wnt-7a) and En1 (ventral) differential expression |
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development of digits happens via what? what causes this?
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apoptosis
FGFs promote production of Msx2, which cooperates with BMP2, BMP4, and BMP 7 to initiate cell death and develop digits |
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order of development of limb tissues and from what they derive?
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1) Cells from Lateral plate mesoderm (LPM) migrate in a give rise to Cartilage, Bone, Joints, Blood vessels
2)Somites give rise to musculature 3) Motor nerve axons extend into limb-Neural Tube 4) Sensory Axons extendent into limb-NCC 5)Schwann Cells/melanocytes-NCC |
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the bone forms from what?
which part of the bone forms first? |
cartilaginous precursors in endochondral ossification
bones form/differential postaxial first, preaxial second (humerus, ulna, 2-5 and their carpals BEFORE radius and thumb) |
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formation of joints is accomplished by transverse splitting of precartilaginous rods of mesenchyme by zones of higher cell density. Wnt-14 stimulates what in these regions?
this is followed by what? antagonist to BMP is needed? what is this? why? |
GDF-5 for normal joint development
this is followed by cell death Noggin is an antagonist of BMP, expressed in joint regions. don't want bone growing there! |
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dorsal mass vs. ventral mass
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dorsal=extensors, soupinators, ab low
ventral=flexors, proton, Ad low |
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sensory neurons use what as a guidance for their direction
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motor neurons
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vasculature of the limbs happens via what
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angiogenesis (sprouting of pre-existing vessels)
all from lateral plate mesoderm still, groups of capillaries form together to make the main arteries and veins, ones not being used, eventually die |
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story for limb development stages. what time frame are we looking at?
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4th-8th weeks
putting your canoe in the water, see a flower BUD drop you PADDLE in the water drifting on the river, beautiful RAYS of sunlight drift underneath a tree, rays become NOTCHED RAYS frog falls into your canoe out of the tree, has WEBBED, DIGITS |
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arms rotate ?
legs rotate? |
arms=90 degrees laterally
legs=90 degrees medially |
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"melia"=?
"dactyly"=? |
melia=limb
dactyly=digits |
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amelia
meromelia ectrodactyly polydactyly syndactyly brachydactyly adadctyly |
amela=absence of entire limb
meromelia=absence of part of limb polyD=excessive # of digits synD=webbing brachyD=shortened digits aD=loss of all digits |
